Metformin use for PCOS during pregnancy raises obesity risk among offspring

Children born to mothers with polycystic ovary syndrome who used metformin during their pregnancies are at increased risk for overweight or obesity at age 4 years, according to findings published in The Journal of Clinical Endocrinology & Metabolism.

Liv Guro Engen Hanem, MD, a PhD candidate in the department of clinical and molecular medicine at the Norwegian University of Science and Technology in Trondheim, Norway, and colleagues evaluated data from two randomized controlled trials on 161 children of mothers with PCOS who used metformin during pregnancy to determine the effect of the agent on offspring growth to age 4 years. In the trials, women were randomly assigned to 1,700 mg or 2,000 mg daily of metformin or placebo from the first trimester to delivery.

Metformin had no effect on offspring height z score at age 4 years, average height z score between 6 months and 4 years, birth length z score, birth weight z score or head circumference at age 1 year.

Offspring of mothers assigned to metformin had higher BMI at age 4 years compared with those whose mothers were assigned to placebo (P = .01). Further, more offspring of mothers assigned to metformin had overweight or obesity at age 4 years compared with those whose mothers were assigned to placebo (OR = 2.17; 95% CI, 1.04-4.61).

“Metformin during pregnancy in women with PCOS increased the risk of overweight and obesity in their children at 4 years of age,” Hanem told Endocrine Today. “Before we have more robust data on the beneficial effects of metformin on pregnancy complications in women with PCOS, it should be used with caution. More evidence is needed regarding the ability of metformin to prevent pregnancy complications associated with PCOS, especially late miscarriages and preterm deliveries. Results from a large randomized controlled trial will be presented later this year. Further, I suggest that all intervention studies with metformin in pregnancy should follow up the long-term health of the offspring.”– by Amber Cox